PORTLAND -- Already like a veteran at age 18, Lexi Thompson led the birdie parade with a 7-under-par 65 Thursday that gave her a one-stroke lead in the LPGA Safeway Classic at Columbia Edgewater Country Club.
Thompson, making her third appearance in the Portland tournament, had an eagle and six birdies and played the four par-5s in 4-under.
Germany's Sandra Gal stood second at 66, after a round that featured seven birdies.
Then came nine players at 67, a group that included world No. 2-ranked Stacy Lewis, former world No. 1 Yani Tseng, 2010 Safeway Classic winner Ai Miyazato and veteran Se Ri Pak.
The field includes about 90 of the top 100 money-winners in 2013, although world No. 1 Inbee Park withdrew Tuesday because of illness and No. 11 Paula Creamer pulled out before her tee time Thursday, citing personal reasons.
The players took advantage of soft conditions created by early-morning rain, thunder and lightning that delayed the start by an hour and led the tour to institute lift, clean and place rules to help players on the wet fairways.
Thompson, who turned pro when she was 15, hit 15 greens on the 6,454-yard layout and credited her iron play for her low score.
"I have been working on tightening up my shots, even with my driver," she said. "I think this is the best my game has ever been. I have been nonstop working on my game, trying to improve little things, and I think it's showing."
Thompson, from Coral Springs, Fla., is looking for her second LPGA victory. She won the Navistar LPGA Classic in September 2011.
Her eagle came on the 463-yard 7th hole, after a drive into the right rough.
"I hit like a three-quarter 6-iron and hit pretty far short, and it rolled all the way up to about six feet above the hole," she said.
Gal, a former University of Florida player who didn't earn a spot on Europe's recently triumphant Solheim Cup team, tied her low round of the season.
The 28-year-old Gal, also with one career LPGA win, called putting the key for her.
"I've been playing really well recently. I just haven't been making a lot of putts," she said.
Numerous groups were still on the course in late afternoon, and it was likely that 90 or more golfers would reach the clubhouse under par.
Others of note with posted scores: Jiyai Shin and Amy Yang, each with a 68, and Morgan Pressel and Karie Webb, both at 69. Defending champ Mika Miyazato opened with a 71.